The Empty Piggy Bank: Why Sleep Drive Matters in Insomnia Treatment. Pt 3.

The Empty Piggy Bank

The rain had started up again, tapping gently against the window. Anna looked more alert than usual, though the circles under her eyes told a different story. She shook her head in disbelief.

Anna: “It doesn’t make sense. I’m exhausted all day, but the second I lie down at night, I feel wired. It’s like my body’s playing a cruel joke.”

I nodded. “That’s one of the most frustrating parts of insomnia—feeling tired but not sleepy. Let me give you a metaphor that might make sense: imagine your sleep drive as a piggy bank.”

Her eyebrows arched. “A piggy bank?”

Therapist: “Yes. Every hour you’re awake, it’s like you’re dropping coins into the bank. By bedtime, the bank should be full, and you can cash it in for a solid night’s rest. That’s how sleep drive works.”

Anna leaned forward, intrigued but skeptical. “Okay… so why does mine feel empty?”

Therapist: “Because of what you’ve been doing during the day. When you nap in the evening, or sleep in late to catch up, it’s like you’re sneaking coins out of the bank before you’ve saved enough. Then, by the time bedtime rolls around, there isn’t enough in there to keep you asleep through the night.”

Understanding Sleep Drive

Anna tilted her head. “So my bank’s running on fumes?”

“Exactly,” I said. “Sleep relies on something called homeostatic sleep drive—it’s the natural pressure that builds the longer you’re awake. Biologically, it comes from a chemical called adenosine. Every time you use energy—thinking, moving, even just staying alert—adenosine collects in your brain. By nighttime, if you’ve been awake long enough, that pressure should be strong enough to push you into sleep.”

Her eyes narrowed. “So just being awake builds it up?”

“Yes, but not just that. Physical activity adds to it, because your body uses more energy. Mental effort—like working, problem-solving, even meaningful conversations—also contributes. Exposure to natural light during the day helps your circadian system sync up, which makes your sleep drive more effective at night. And consistency matters: waking up at the same time every morning ensures you’re giving yourself enough hours of wakefulness to build a full ‘bank.’”

Anna gave a small nod, then frowned. “So when I nap after work, or sleep in on weekends, I’m cutting into that build-up.”

“Exactly. It feels like relief in the moment, but you’re spending coins before your piggy bank is full. By the time bedtime comes, there isn’t enough left to keep you asleep.”

Perpetuating the Cycle

Anna groaned and pressed her palms to her eyes. “No wonder I’m stuck. I nap on the couch after work just to get through the evening. Then on weekends, I sleep in until ten or eleven trying to ‘catch up.’ I thought I was helping myself, but I’ve been robbing my piggy bank before it’s even full.”

I nodded gently. “That’s the trap so many people fall into. Those strategies feel like survival—and in the short term, they do take the edge off. But in the long run, they drain the very pressure your body needs to sleep at night. It’s like trying to fill a water tank while also poking holes in the bottom.”

She gave a bitter laugh. “So I’ve been undoing all my own progress.”

“Not undoing—just coping in ways that backfire. You’ve been doing what anyone would do when they’re desperate: grabbing rest whenever you can. But these coping habits are what we call perpetuating factors. They keep insomnia alive long after the original stress that started it has passed.”

Anna lowered her hands, her face softening as understanding replaced frustration. “So the very things I thought were helping… are the things keeping me trapped.”

Introducing Sleep Restriction

Anna leaned back, arms crossed again. “So if naps and sleeping in are draining the bank… what do I do instead? Just stay tired forever?”

I smiled softly. “Not forever. But this is where one of the most effective insomnia treatments comes in. It’s called sleep restriction—or more accurately, sleep consolidation.”

Her eyebrows shot up. “Restriction? That sounds awful. I already feel like I’m not sleeping enough, and now you’re saying I should cut back even more?”

“I know it sounds counterintuitive,” I said. “But here’s the logic: right now, your body doesn’t connect bed with sleep. It connects bed with lying awake, worrying, clock-watching. By limiting the time you spend in bed, we rebuild your sleep drive and strengthen the association between bed and sleep.”

Anna tilted her head, still skeptical. “So instead of chasing more hours, I’m supposed to… sleep less?”

“At first, yes. We start by matching your time in bed to the actual amount of sleep you’re getting. That way, your piggy bank fills up fully each day, and when bedtime comes, your sleep pressure is strong enough to carry you through. As your nights become more solid, we’ll gradually expand your time in bed again. It’s about quality first, then quantity.”

She let out a low whistle. “Feels like training wheels for my sleep.”

“Exactly,” I said, smiling. “We’re rebuilding the foundation. Once it’s sturdy, we can stretch it further. But if we try to force it all at once, the cracks just widen.”

Preparing for the Next Step

Anna slouched back into the chair, arms unfolding just a little. “I can see the logic. I’ve been pouring energy into all the wrong fixes—naps, gadgets, sleeping in. Maybe it’s time to stop fighting and actually let my body earn the sleep it needs.”

“That’s the shift,” I said. “Sleep restriction isn’t about punishing you or making you more tired. It’s about giving your brain a clear signal: the bed is for sleeping. Once your sleep drive is strong and your body relearns that connection, nights won’t feel like a battle anymore.”

She worried her lip between her teeth. “So it won’t feel great at first.”

“It might be tough in the beginning,” I admitted. “You’ll feel sleepy earlier in the evening, and mornings may be rough. But remember—it’s temporary. The goal is to reset your system so that sleep comes naturally again. Think of it like training: uncomfortable at first, but it builds strength.”

Anna nodded slowly, a spark of determination in her tired eyes. “Alright. If this is the foundation, then I want to give it a real shot. I can’t keep doing what I’ve been doing.”

I smiled. “That’s all we need to begin. From here, every step builds on this.”

Therapist’s Note: Key Takeaways from This Session

• Sleep drive builds up through wakefulness, activity, and consistent daily routines.

• Coping habits like napping, sleeping in, using caffeine, or going to bed too early drain sleep drive and keep insomnia alive.

• Sleep restriction (sleep consolidation) limits time in bed to rebuild stronger sleep pressure and re-establish the connection between bed and sleep.

•The process may feel difficult at first, but it lays the foundation for lasting, natural sleep.